3C-SiC thin films were grown on Si(1 0 0) substrates at 1200 degrees C by atmospheric pressure chemical vapor deposition. We performed an in-depth study on the effect of propane/silane ratio (it is expressed by C/Si which means the ratio of C atom to Si atom in propane and silane) on crystalline quality and microstructure of 3C-SiC thin films. The 3C-SiC thin films exhibit epitaxial nature with pyramid-like morphology or polycrystalline columnar grains with rounded shape, which are dependent on C/Si ratio. The growth mechanism of 3C-SiC film with different C/Si ratios is discussed based on the cross-sectional transmission electron microscopy characterization. The changes in crystalline and microstructure with increasing C/Si ratio are attributed to high secondary nucleation rate. (C) 2012 Elsevier B. V. All rights reserved.